1. Field of the Invention
The present invention relates to a battery system for secondary batteries.
2. Description of the Related Art
A battery system in the related art includes a plurality of battery groups, each formed by connecting in series a plurality of battery cells, connected so as to constitute a battery module, and a lower-order control device that monitors the states of the battery cells, installed in correspondence to each battery group. Such a battery system in the known art may execute diagnosis to determine whether a battery cell is in an overcharged state or an over-discharged state (see, for instance, Japanese Laid Open Patent Publication No. 2005-318751). The battery system may be further equipped with a function of diagnosing the operating state of a balancing circuit installed to minimize differences in the level of charge among individual battery cells.